Always initialize THD::thread_stack: it's used in

check_stack_overrun().

sql/slave.cc

@@ -3446,6 +3446,7 @@ slave_begin:
   THD_CHECK_SENTRY(thd);
 
   pthread_detach_this_thread();
+  thd->thread_stack= (char*) &thd; // remember where our stack is
   if (init_slave_thread(thd, SLAVE_THD_IO))
   {
     pthread_cond_broadcast(&mi->start_cond);
@@ -3454,7 +3455,6 @@ slave_begin:
     goto err;
   }
   mi->io_thd = thd;
-  thd->thread_stack = (char*)&thd; // remember where our stack is
   pthread_mutex_lock(&LOCK_thread_count);
   threads.append(thd);
   pthread_mutex_unlock(&LOCK_thread_count);

sql/sql_acl.cc

@@ -158,6 +158,7 @@ my_bool acl_init(bool dont_read_acl_tables)
   */
   if (!(thd=new THD))
     DBUG_RETURN(1); /* purecov: inspected */
+  thd->thread_stack= (char*) &thd;
   thd->store_globals();
   /*
     It is safe to call acl_reload() since acl_* arrays and hashes which
@@ -3263,6 +3264,7 @@ my_bool grant_init()
 
   if (!(thd= new THD))
     DBUG_RETURN(1);				/* purecov: deadcode */
+  thd->thread_stack= (char*) &thd;
   thd->store_globals();
   return_val=  grant_reload(thd);
   delete thd;

sql/sql_class.cc

@@ -517,6 +517,12 @@ void THD::awake(THD::killed_state state_to_set)
 
 bool THD::store_globals()
 {
+  /*
+    Assert that thread_stack is initialized: it's necessary to be able
+    to track stack overrun.
+  */
+  DBUG_ASSERT(this->thread_stack);
+
   if (my_pthread_setspecific_ptr(THR_THD,  this) ||
       my_pthread_setspecific_ptr(THR_MALLOC, &mem_root))
     return 1;

sql/sql_insert.cc

@@ -1723,6 +1723,7 @@ pthread_handler_t handle_delayed_insert(void *arg)
 #endif
 
   DBUG_ENTER("handle_delayed_insert");
+  thd->thread_stack= (char*) &thd;
   if (init_thr_lock() || thd->store_globals())
   {
     thd->fatal_error();

sql/sql_parse.cc

@@ -1097,6 +1097,7 @@ pthread_handler_t handle_one_connection(void *arg)
   VOID(sigemptyset(&set));			// Get mask in use
   VOID(pthread_sigmask(SIG_UNBLOCK,&set,&thd->block_signals));
 #endif
+  thd->thread_stack= (char*) &thd;
   if (thd->store_globals())
   {
     close_connection(thd, ER_OUT_OF_RESOURCES, 1);
@@ -1110,7 +1111,6 @@ pthread_handler_t handle_one_connection(void *arg)
     int error;
     NET *net= &thd->net;
     Security_context *sctx= thd->security_ctx;
-    thd->thread_stack= (char*) &thd;
     net->no_send_error= 0;
 
     if ((error=check_connection(thd)))
@@ -5288,6 +5288,7 @@ bool check_stack_overrun(THD *thd, long margin,
 			 char *buf __attribute__((unused)))
 {
   long stack_used;
+  DBUG_ASSERT(thd == current_thd);
   if ((stack_used=used_stack(thd->thread_stack,(char*) &stack_used)) >=
       (long) (thread_stack - margin))
   {
@@ -6737,7 +6738,10 @@ bool reload_acl_and_cache(THD *thd, ulong options, TABLE_LIST *tables,
       allocate temporary THD for execution of acl_reload()/grant_reload().
     */
     if (!thd && (thd= (tmp_thd= new THD)))
+    {
+      thd->thread_stack= (char*) &tmp_thd;
       thd->store_globals();
+    }
     if (thd)
     {
       (void)acl_reload(thd);

sql/sql_udf.cc

@@ -159,6 +159,7 @@ void udf_init()
     DBUG_VOID_RETURN;
   }
   initialized = 1;
+  new_thd->thread_stack= (char*) &new_thd;
   new_thd->store_globals();
   new_thd->db= my_strdup("mysql", MYF(0));
   new_thd->db_length=5;

sql/tztime.cc

@@ -1532,6 +1532,7 @@ my_tz_init(THD *org_thd, const char *default_tzname, my_bool bootstrap)
   */
   if (!(thd= new THD))
     DBUG_RETURN(1);
+  thd->thread_stack= (char*) &thd;
   thd->store_globals();
 
   /* Init all memory structures that require explicit destruction */